1. Field of the Invention
A transporter enabling the straddling of longitudinally-extending rows, such as are found in a plant nursery environment, wherein the transporter further enables a longitudinal conveyance between four vertical uprights for non-palletized items, such as potted plant articles.
2. Brief Description of the Prior Art
Prior workers have developed straddle-type transporter vehicles, for particular purposes and with unique capabilities for the function intended. For example, Sturgill, U.S. Pat. No. 4,219,094, illustrates a multi-wheel straddle-type vehicle having central lifting means, wherein his particular structural connections of the vertical corner members provide surprisingly good operation over uneven terrain.
Washburn, U.S. Pat. No. 3,534,880, illustrates a non-powered straddle-type vehicle, for the purpose of supplying a portable, hand-operated mechanism to transport a carpet roll, or other form of hollow core device, which conveniently may be placed upon a transversely extending core member, which in turn can vertically be raised or lowered between a pair of longitudinally extending frames.
Colt et al., U.S. Pat. No. 3,064,745 illustrate an approach to materials handling wherein a fixed conveyor rides upon a powered vehicle bed which has the ability of various steering and power transmission directly from motors to individual wheels. The present invention shares certain of this known technology, in the sense that separate power is provided to at least two of the four independent wheel assemblies. Similarly, Ehrenberg, U.S. Pat. No. 4,089,384 illustrates known traction driving for separate independent wheel control, wherein a central hydrauic motive power source is employed to apply traction to individual wheel assemblies. The present invention has a preferred embodiment with electric motive drives, through hydraulic equivalents are, of course, contemplated for the identical functions required.
Carter, U.S. Pat. No. 3,859,610 illustrates a known form of freight transporter wherein an elevation function is provided by a scissor-jack mechanism, beneath a roller assembly. Carter also illustrates a single chain which is attached to individual slats, wherein the slats are themselves supported upon a plurality of rollers, as they are used to convey.
Carder et al., U.S. Pat. No. 3,655,076 illustrate a pallette handling system, wherein an unpowered series of dollies are interconnected with a motive power source, in order to transfer material onto a carrying device. Carder et al. also illustrates those prior art approaches which require separate vehicle elements, to move material from a first elevation to a second elevation.
The patents to Reffle, U.S. Pat. No. 3,534,825 and Rabjohn, U.S. Pat. No. 3,380,546, are noted to illustrate known vehicle drive systems wherein individual motors are employed directly to drive, through worm and pinion or chain-drive arrangements, individual wheels of a vehicle.
The patent to Huxley, U.S. Pat. No. 3,861,535, illustrates another known form of straddle vehicle, wherein a forklift mechanism is arranged to be positionable at various vertical heights, in response to a driver input.
The prior art devices, in each case, evidence a unique configuration for the purpose intended, for example, aircraft unloading, or a motive drive with the ability to distribute unsprung weight, for example. However, it has remained a problem in certain applications, such as harvesting and distribution of nursery stock, to accommodate the topography of a nursery, as well as the individual pots or plants which are being nurtured. In particular, in a nursery environment, it is critical to have rapid access to various locations in the field, for selecting among desired items, without inordinate manpower waste through following narrow paths and manually moving a desired selection back to a waiting truck, for example. The present invention has the unique ability of enabling a sequential loading of a longitudinally-extending conveyor means at various locations, and at various vertical elevations, and also the ability to convert a generally longitudinal direction of travel, to a complete orthogonal or lateral direction of travel, simply by an operator choice at his control system.
It is also very desirable in a commercial nursery environment, to have a vehicle which is capable of a creep, wherein that slow vehicle movement can be coordinated with a motion of a conveyor system, for timing of on-take onto the conveyor, and off-take of the conveyor at a rearward station, for example, by a second crew at selected points along a path of vehicle travel. While the present invention provides a side-straddle location for an operator, it easily is adaptable to a remote control position, where an operator can sit in an overhung front position, for example, and participate in the loading of non-palletized materials, as the entire conveyor is selectively bumped or indexed, from his operating position.
It also would be desirable to have a straddle device which quickly and easily could overcome fixed obstacles extending between the longitudinally-extending sides of the device, so that large nursery stock, for example, can be by-passed without need for diverting the transporter around what otherwise would be an obstacle to continued movement in a direction.
Accordingly, it is the primary object of the invention to provide an improved multi-wheel transporter vehicle of the straddle-type, comprising the ability selectively to be driven through two or more of the four wheel assemblies at the bottom of four vertically-extending columns but with steering control at each wheel assembly. A related object of the invention is to provide such a vehicle having the ability to independently control the steering of all four wheel assemblies to enable a quick change from normal to a complete lateral motion, if desired. A related and further object of the invention is a transporter vehicle having a control system sensitive to the needs of independent controls for various conveyor speeds and vertical positions, to enable a number of combinations of speeds and directions for the various driving functions enabled by the device.
These and other objects and advantages will become more apparent from a review of the written description of the invention which follows, as also illustrated and disclosed in the accompanying drawings.